CN1252488C - Magnetic resonance imaging method and system - Google Patents

Magnetic resonance imaging method and system Download PDF

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CN1252488C
CN1252488C CN 01801406 CN01801406A CN1252488C CN 1252488 C CN1252488 C CN 1252488C CN 01801406 CN01801406 CN 01801406 CN 01801406 A CN01801406 A CN 01801406A CN 1252488 C CN1252488 C CN 1252488C
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magnetic resonance
matrix
amp
resonance signals
image
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CN1380983A (en
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K·P·普吕斯曼
M·韦格
P·贝尔纳特
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皇家菲利浦电子有限公司
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00Arrangements or instruments for measuring magnetic variables
    • G01R33/20Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48NMR imaging systems
    • G01R33/54Signal processing systems, e.g. using pulse sequences, Generation or control of pulse sequences ; Operator Console
    • G01R33/56Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/561Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
    • G01R33/5611Parallel magnetic resonance imaging, e.g. sensitivity encoding [SENSE], simultaneous acquisition of spatial harmonics [SMASH], unaliasing by Fourier encoding of the overlaps using the temporal dimension [UNFOLD], k-t-broad-use linear acquisition speed-up technique [k-t-BLAST], k-t-SENSE
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00Arrangements or instruments for measuring magnetic variables
    • G01R33/20Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48NMR imaging systems
    • G01R33/54Signal processing systems, e.g. using pulse sequences, Generation or control of pulse sequences ; Operator Console
    • G01R33/56Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/563Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution of moving material, e.g. flow contrast angiography
    • G01R33/5635Angiography, e.g. contrast-enhanced angiography [CE-MRA] or time-of-flight angiography [TOF-MRA]

Abstract

提供了一种磁共振成像方法,其中根据来自各自的信号通道中的磁共振信号重建磁共振图像。 There is provided a magnetic resonance imaging method, wherein the image based on magnetic resonance signals from the respective signal path in the reconstructed magnetic resonance. 更具体地说,单独的信号通道与用作磁共振信号的接收器天线的各自的表面线圈相关。 More specifically, individual signal channels associated with the magnetic resonance signals is used as a receiver antenna respective surface coils. 使用k-空间的子采样采集磁共振信号。 K- space using sub-sampling resonance signals are acquired. 在规则的正方形网格上执行再采样,由此在磁共振图像的重建的过程中能够实现快速傅立叶变换。 Resampling performed on a regular square grid, whereby the magnetic resonance image reconstruction process of the fast Fourier transform can be realized. 此外,以接收器天线、即表面线圈的空间灵敏度分布为基础实施重建,由此将在子采样的磁共振信号中的不同的空间位置的贡献分开。 Furthermore, the receiver antenna, i.e., the spatial distribution of the sensitivity of the surface coil embodiment based reconstruction, thereby separating the contributions of the different spatial position of the magnetic resonance signals in the sub-sampling. 优选地是,在k-空间中采用螺旋状采集轨迹。 Preferably, collected using a spiral trajectory in k- space.

Description

磁共振成像的方法及系统 MR imaging method and system

背景技术 Background technique

本发明涉及一种形成磁共振图像的磁共振成像方法,其中借助接收天线通过多个信号通道采集磁共振信号,其单独的接收天线具有各自的灵敏度分布。 The present invention relates to a magnetic resonance imaging method of forming magnetic resonance images, wherein the magnetic resonance signals acquired by means of the receiving antenna through a plurality of signal channels, which have respective separate receiver antenna sensitivity distribution.

本发明还涉及一种磁共振系统。 The present invention also relates to a magnetic resonance system.

文章“Coil Sensitivity Encoding for Fast MRI”(KPPrussmann等人的,在Proceedings ISMRM(1998)579上发表的)公开了一种磁共振成像方法和实施这种磁共振成像方法的磁共振系统。 Article "Coil Sensitivity Encoding for Fast MRI" (KPPrussmann et al., In Proceedings ISMRM (1998) published in 579) discloses a method for magnetic resonance imaging and magnetic resonance imaging systems of this method of magnetic resonance.

公知的磁共振成像方法有缩写为SENSE的方法。 There abbreviated SENSE method known magnetic resonance imaging method. 这种公知的磁共振成像方法使用接收线圈的形式的接收天线。 The known magnetic resonance imaging method used in the form of a receiving coil receiving antenna. 这种磁共振成像方法使用所采集的磁共振信号的子采样以降低对用于所需的视场的k-空间中和在k-空间中对于磁共振图像的所需的空间分辨率足够大的区域上以一采样密度扫描k-空间所需的时间,值得注意的是,在k-空间中沿着它执行扫描的相应的线在k-空间中设置得比所需空间分辨率需要的设置更远。 This magnetic resonance imaging method using the magnetic resonance signals acquired sub-sampling to reduce the space required for k- field of view in the k- space and the space required for the magnetic resonance image resolution is sufficiently large time sampling density region to a scanning k- space required, it is noteworthy that the respective lines along which the scanning is performed in the k- space set lower than the desired spatial resolution required in the k- space set farther. 换句话说,在k-空间中“线被跳过”。 In other words, in the k- space "line is skipped." 由于这种“在k-空间中线的跳过”,因此采集磁共振信号需要较少的时间。 Because of this "line in the k- space skip", the magnetic resonance signals acquired thus less time is required. 根据来自单独的接收线圈的子采样的磁共振信号重建接收线圈图像。 Reconstructs the received magnetic resonance signals sampled in accordance with the sub-coil image from the individual receiving coil. 由于这种子采样,减小了实际的视场,因此在这种接收线圈图像中产生了反向叠加和混叠伪影。 Due to this sub-sampling, the actual field of view is reduced, thus creating reverse overlay and aliasing artifacts such receiver coil images. 根据灵敏度分布从接收线圈图像中得出磁共振图像,由此基本或者甚至完全消除了在该磁共振图像中的混叠伪影。 The magnetic resonance image is derived from a sensitivity profile of the receiving coil image, thereby substantially or even completely eliminate the aliasing artifacts in the magnetic resonance image. 这种无混叠操作将磁共振图像扩大到所需的视场。 This non-aliasing operation to expand the field of view of the magnetic resonance image is required.

在放射学实践中已经发现采集磁共振信号所需的时间需要相当大地进一步减少。 In radiology practice it has been found that the desired magnetic resonance signal acquisition time required considerably further reduced. 已经发现,特别是对于对快速运动的组织部位,例如紧张患者的跳动的心脏,进行高空间分辨率成像的磁共振成像方法以及对于MR血管造影方法来说,需要实质性地减少磁共振成像的采集时间,本发明的一个目的是提供一种磁共振成像方法,其中磁共振信号的采集时间比在使用公知的SENSE技术时所需的采集时间短得多。 It has been found, especially for fast-moving parts of the organization, such as the beating heart nervous patients, magnetic resonance imaging method for high spatial resolution imaging and a method for MR angiography, the need to substantially reduce magnetic resonance imaging acquisition time, an object of the present invention is to provide a magnetic resonance imaging method, wherein the magnetic resonance signal acquisition time is much shorter than that required when using the known SENSE technique acquisition time.

通过根据本发明的磁共振成像方法实现本目的,其中通过噪声相关矩阵表示在单独的信号通道之间的噪声相关性,这里,使用子采样采集磁共振信号,在规则的采样网格上从所采集的磁共振信号中再采样出规则再采样的磁共振信号,通过块对角矩阵或带对角矩阵对该噪声相关矩阵进行近似,位于近似的噪声相关矩阵的主对角线周围的预定带之外的矩阵元素的值为零,以及在灵敏度分布和近似噪声相关矩阵的基础上根据已经从所采集的磁共振信号中进行了再采样的规则再采样的磁共振信号重建磁共振图像。 This object is achieved according to the present invention is magnetic resonance imaging method by which the noise represents the correlation between individual channels through the signal noise correlation matrix, where the use of sub-sampled magnetic resonance signals acquired on a regular sampling grid from the magnetic resonance signals acquired in the re-sampling magnetic resonance signals resampling rule, be approximated with a diagonal matrix or correlation matrix of the diagonal matrix by the block noise, a predetermined band located around the main diagonal of the noise correlation matrix is ​​approximated matrix element values ​​other than zero, and the magnetic resonance signals resonance image is reconstructed on the basis of the sensitivity distribution and the approximate noise correlation matrix has been performed according to the rules from the acquired magnetic resonance signals resampled in resampling.

在利用灵敏度分布的同时从在k-空间中子采样的磁共振信号中得出磁共振图像。 A magnetic resonance image derived from magnetic resonance signals sampled in k- space neutrons while using sensitivity distribution. 子采样意味着在k-空间中采样是较粗糙的,即在k-空间中具有的分辨率比用于磁共振图像视场所足够的分辨率要粗糙。 Sub-sampling means sampling is coarser in k- space, i.e. having the k- space resolution to a sufficient resolution coarser than the field of view of the magnetic resonance image. 在一种磁共振成像方法中,磁共振图像的亮度变化的最小波长与视场相关。 In a magnetic resonance imaging method, the wavelength of the minimum luminance change associated with the field of view of the magnetic resonance image. 最小波长尤其与视场的大小成比例并与在k-空间中的采样密度成比例。 In particular, the minimum wavelength is proportional to the size of the field of view and the sampling density is proportional to the k- space. 在子采样的情况下,采样比足够用于磁共振图像的视场的尺寸所需的采样要粗糙。 Required in the case of sampling the sub-sampled, the sampling ratio sufficient for magnetic resonance image size of the field of view to be rough. 信号值根据它们在k-空间中的波矢量和根据灵敏度分布被进行编码。 The wave signal value thereof k- space vector and encoding is performed according to the sensitivity profile. 各自的接收天线的磁共振信号对应于各自的信号通道。 A respective receiving antenna magnetic resonance signals corresponding to the respective signal channels. 贡献于每个信号通道中的信号的噪声是来自相关的信号通道和(原则上)所有的其它信号通道的噪声的贡献的线性组合。 The contribution of the noise signal in each signal channel is a linear combination from the associated signal path and (in principle) all the noise contribution of the other signal path. 接收天线是例如对磁共振信号敏感的接收线圈。 Receiving magnetic resonance signals, for example, the antenna is sensitive receiver coil. 优选地是,使用表面线圈作为接收天线。 Preferably, the surface coil used as a receiving antenna. 将这种表面线圈设置在要检查的患者的身体上,这种表面线圈显著地拾取在要检查的患者的身体内产生的在表面线圈附近位置的磁共振信号。 Such surface coils disposed on the body of the patient to be examined, such a significant surface coil pickup in the patient to be examined at a position near the surface of magnetic resonance signals generated in the coil body. 信号通道之间的噪声相关用噪声相关矩阵表示。 A noise correlation between the signal channels represented by the noise correlation matrix. 对用于诊断质量的磁共振图像的实际共振信号的数目,如果没有采取措施,在k-空间并以灵敏度分布为基础将磁共振信号解码成用于图像矩阵中的单独的像素位置的像素值造成了要求较高的计算容量和较长的计算时间的矩阵求逆问题。 The actual number of resonance signals for the magnetic resonance image of diagnostic quality, if no measures are taken, and sensitivity to spatial distribution based on the decoded k- magnetic resonance signals into an image position of the individual pixels of the pixel matrix values resulting in higher demand matrix computing capacity and long computation time inversion problem. 噪声相关问题可以由单位矩阵、块对角矩阵或两对角矩阵近似,所有这些矩阵都是块对角矩阵或带对角矩阵的特定的实例。 Correlation matrix of the noise problem can be units, or both of a block diagonal matrix diagonal matrix approximation, these matrices are all examples of specific block diagonal matrix with a diagonal matrix or. 根据SENSE算法从子采样磁共振信号中重建磁共振图像包括使在磁共振图像中的噪声特性最佳化。 The algorithm SENSE magnetic resonance signals from the sub-resonance image is reconstructed comprises optimizing noise in the magnetic resonance image. 这个最佳化涉及噪声相关矩阵,该噪声相关矩阵包含在所采样的磁共振信号中的对角元素噪声和通过不同的接收器天线所采集的相应的采样的磁共振信号之间的非对角元素噪声相关中。 The Optimizer relates to the noise correlation matrix, the correlation matrix of the noise contained in the magnetic resonance signals sampled in between the non-diagonal elements of the magnetic resonance signals and the corresponding sampling noise by a different receiver antennas collected diagonal noise-related elements in. 可以看出作为近似可以用单位矩阵替代噪声相关矩阵。 It can be seen as an approximate matrix can substitute noise correlation matrix. 作为一种替换,更巧妙的近似基于这样的认识:噪声相关基本随时间恒定。 As an alternative, more subtle approximation based on the recognition: noise correlation substantially constant over time. 因此,表现出可以通过具有稀疏结构,即近似(块)对角线的矩阵充分地描述噪声相关。 Thus, by showing sparse structure, i.e., approximately (block) diagonal fully described noise correlation matrix. 这种稀疏结构允许对来自各自的接收器线圈的子采样的磁共振信号进行实际的再采样或再装入到实际通道中作为来自单独的接收器线圈的子采样的磁共振信号的线性组合。 This sparse structure allows magnetic resonance signals from the respective sub-sampled receiver coil of the actual re-sampling or re-charged to a linear combination of the physical channel as a child from a separate receiver coil sampled magnetic resonance signals. 对噪声相关矩阵进行使其成为可逆的左三角矩阵和它的厄密共轭的矩阵的乘积的所谓的Cholesky分解,由此获得这种线性组合中的权重。 The noise correlation matrix for Cholesky decomposition to become a so-called matrix is ​​invertible left triangular matrix and its Hermitian are multiplied, thereby obtaining a linear combination of such weights. 那么,连系实际通道的有效噪声相关矩阵是单位矩阵。 Then, the effective noise associated with the actual channel correlation matrix is ​​an identity matrix. 根据本发明已经发现,在实际中在来自单独的接收天线的磁共振信号中的噪声贡献之间的相关可用具有仅来自主对角线附近的元素的贡献的较简单的矩阵进行适当地近似。 According to the invention it has been found, in practice, the available correlation between the noise contribution from the magnetic resonance signals in the individual receiving antenna has a relatively simple matrix contribution from only the vicinity of the main diagonal element is suitably approximated. 甚至已经发现,这种噪声相关可以用单位矩阵替换。 Even it has been found that this can be replaced with the noise correlation matrix. 已经发现,这种简化极大地减轻了矩阵求逆问题,因此仅要求相对较短的计算时间和有限的计算容量。 It has been found that this simplification greatly reduces the matrix inversion problem, thus requiring only a relatively short calculation time and calculation capacity is limited. 因此在较短的时间周期内可以从磁共振信号中重建磁共振图像。 A magnetic resonance image can be reconstructed from the magnetic resonance signals in a short period of time. 还发现,在实际中在一分钟内可以从子采样磁共振信号中重建128×128图像矩阵(因此N=128)。 Also it found that, in practice, be sampled magnetic resonance signals in the 128 × 128 image reconstructed from the sub-matrix in one minute (so N = 128). 还已经发现,根据灵敏度分布在磁共振图像的重建中的噪声相关矩阵的近似对磁共振图像的诊断质量没有明显不利的影响。 It has also been found that no significant adverse effect on the quality of the diagnostic magnetic resonance image from the approximate sensitivity distribution in the reconstructed magnetic resonance image noise correlation matrix. 这意味着磁共振图像具有合适的对比分辨率,因此在磁共振图像中合适地可视地再现了低对比度细节。 This means that a magnetic resonance image having suitable contrast resolution, and therefore suitably in the magnetic resonance image being reproducible visibly low contrast detail. 通过将公知的快速傅立叶变换应用到规则再采样磁共振信号中显著地进一步降低了磁共振图像的重建时间。 By well-known Fast Fourier Transform rule applied to another magnetic resonance signal significantly further reduces the magnetic resonance image reconstruction time. 规则(再)采样意味着在规则的正方形网格上对在k-空间中的磁共振信号进行采样。 Rule (re) sampling means magnetic resonance signals in k- space is sampled on a regular square grid. 已经发现,对于N×N图像矩阵,这种简化使矩阵求逆问题从N4的数量级降低到了N2或N2logN的数量级。 It has been found, for a matrix of N × N image, this simplification makes the matrix inversion problem is reduced from the order of N4 to N2 or N2logN of magnitude.

本发明提供来了选择用于磁共振信号的采集的、循着k-空间的轨迹的高度自由。 The present invention provides to a height of free choice for acquiring magnetic resonance signals follow the trajectory of the k- space. 根据本发明这种采集轨迹造成了k-空间的非规则采样。 Causing irregular k- space is acquired in accordance with the present invention, this sampling trajectories. 尤其是在磁共振信号的采集的过程中不需要在k-空间中对规则的正方形网格进行采样。 Especially not required during the collection of magnetic resonance signals sampled in a regular square grid in k- space. 因此,例如,可以以不同的速度穿过k-空间的相应的部分。 Thus, for example, through a corresponding portion of k- space at different speeds. 本发明尤其是提供了选择穿过k-空间的基本螺旋状轨迹的可能性。 The present invention particularly provides the possibility of substantially spiral trajectory through the choice of the k- space. 然后首先从k-空间的中心部分中采集磁共振信号,对此利用相对小的大小的波形矢量,其后在波形矢量的大小连续快速地增加的同时采集磁共振信号。 First, the central portion is then collected from magnetic resonance signals k- space, this shape vector with a relatively small size, the size of the magnetic resonance signals acquired subsequent waveform vector is rapidly increased at the same time continuously. 沿着k-空间中螺旋状的轨迹或包括一个或多个螺旋状步长的轨迹的这种采集特别适合于在MR血管造影方法中使用。 K- space along a helical trajectory or comprises one or more long helical trajectories of this acquisition step is particularly suitable for use in a method of MR angiography. 在这种方法里,在给患者施加了对比剂、例如通过静脉内注射对比剂之后立即形成要检查的患者的磁共振图像。 In this method, the contrast agent is applied to a patient, for example, a magnetic resonance image of the patient to be examined by intravenous injection immediately after the contrast agent. 来自k-空间的中心的磁共振信号主要涉及在磁共振图像中相当粗糙的结构,包括要检查的患者的脉管系统的动脉部分。 Magnetic resonance signals from the center of k- space in the magnetic resonance image relates rather rough structure, comprising a portion of the arterial vasculature of a patient to be examined. 脉管系统的静脉部分主要包括更细微得多的结构。 The main part of the venous vasculature, including a much finer structure. 在跟随了螺旋状轨迹之时,在对比剂达到静脉之前从动脉部分采集磁共振信号。 When the helical trajectory followed, the contrast agent reaches veins before collecting magnetic resonance signals from the sections of the arteries. 此外,因为使用了子采样,因此磁共振信号的采集并不要求较长的时间。 Further, since the sub-sampled magnetic resonance signals acquired thus does not require a long time. 磁共振信号的子采样的采集和沿着螺旋状轨迹的扫描的组合使得能够以较高的空间分辨率快速地采集脉管系统的动脉部分的磁共振图像。 And combinations subsampled collected magnetic resonance signals along a helical trajectory such that a magnetic resonance image of the scanned portion of the arterial vasculature can be quickly acquired at a higher spatial resolution.

根据在从属权利要求中所限定的下文的实施例详细地描述本发明的这些方面和其它的方面。 These aspects of the invention and other aspects described in detail below according to embodiments in the dependent claims as defined.

优选地是,从来自单独的信号通道因而来自各自的接收天线中的磁共振信号重建各自的接收线圈图像。 Preferably, the magnetic resonance signals thus received from the respective antennas in the respective reconstructed images from the receiver coil signal from a separate channel. 优选地是将接收线圈用作接收天线。 Preferably the receiving coil as a receiving antenna. 由于来自单独的信号通道的磁共振信号的子采样,在这种接收线圈图像中产生了混叠伪影比如反向叠加现象。 Since the sub-sampled magnetic resonance signals from a separate signal path, resulting in aliasing artifacts, such as the reverse phenomenon superimposed image in which the receiving coil. 使用根据本发明的近似的噪声相关矩阵对接收线圈图像进行重建。 Use reconstruct an image receiving coil according to the approximate noise correlation matrix of the present invention. 磁共振图像是根据灵敏度分布从接收线圈图像中得出的。 Magnetic resonance image is derived from the received image according to the sensitivity distribution of coil. 根据接收线圈图像和灵敏度分布重建磁共振图像本身称为SENSE方法。 The receiver coil images and the sensitivity profiles themselves called resonance image is reconstructed SENSE method. 这种SENSE方法本来由Prussmann等人在Proceedings ISMRM(1998)579上发表的文章和Prussmann和Weiger在MRM42(1999)pp.952-962的文章中公开。 This method would have made Prussmann SENSE et al. (1998) 579 published in the Proceedings ISMRM articles and Prussmann and Weiger disclosed in the article MRM42 (1999) pp.952-962 in. SENSE方法能够实现磁共振信号的子采样的采集,由此能够降低磁共振信号的采集所需的时间。 SENSE method enables acquisition sub-sampled magnetic resonance signals, thereby reducing the time required for the acquisition of magnetic resonance signals.

另外,通过对子采样的磁共振信号进行组合,在利用灵敏度分布的同时从子采样的磁共振信号形成全采样的磁共振信号是可能的。 Further, by combining the sub-sampled magnetic resonance signals, the magnetic resonance signals while using a sensitivity profile is formed from sub-sampled magnetic resonance signals are possible in the whole sample. 磁共振图像根据通过组合所获得的磁共振信号进行重建。 The magnetic resonance image is reconstructed from the magnetic resonance signals obtained by combining. 在k-空间的各种磁共振信号然后被组合以填充在k-空间中的在采集过程中已经跳过的线。 K- various magnetic resonance signals are then combined to a space in the acquisition process has been skipped in the line fill k- space. 这种方法公知为只取首字母的缩写词SMASH,本身来自美国专利US5,910,728。 This method is known abbreviations Acronym SMASH only take itself from the U.S. Patent No. US5,910,728.

当使用接收线圈或表面线圈作为接收天线时,接收线圈的线圈灵敏度分布对应于接收天线的灵敏度分布。 When receiving coil or surface coil as a receiving antenna, coil sensitivity distribution of receiving coil sensitivity profile corresponding to the receiving antenna.

优选地是,接收线圈优选基本上对电感去耦。 Preferably, the receiving coils are preferably substantially decoupling inductor. 由于接收线圈的电感耦合程度较低,因此噪声水平和噪声相关都较低。 Due to the low degree of inductively coupled receiving coil, and thus the noise level are low noise correlation. 由此降低了磁共振图像的噪声水平。 Thereby reducing the noise level of the magnetic resonance image.

优选地是,使用迭代求逆算法进行磁共振图像的重建。 Preferably, the iterative inversion algorithm to reconstruct the magnetic resonance image. 即,通过来自子采样的磁共振信号的迭代对磁共振图像进行重建。 I.e., reconstruct a magnetic resonance image from the magnetic resonance signals by an iterative sub-sampled. 以某一初始矢量开始,迭代算法产生一个近似解的级数,这个级数收敛到精确的解。 Starting with some initial vector, iterative algorithm to generate a series of approximate solution, the series converges to the exact solution. 有多个这种技术来处理较大的线性系统。 A plurality of such techniques to handle larger linear system. 所谓的共轭梯度(cg)法特别适合。 A so-called conjugate gradient (CG) method is especially suitable. 在一方面,为很有效的计算,它可以与FFT相组合。 In one aspect, the calculation is very effective, it can be combined with FFT. 在另一方面,CG迭代并不要求确保收敛的特殊规定。 On the other hand, CG iteration does not require special provisions to ensure convergence. 假若所包含的矩阵是正定的,它可安全地收敛,对于将重建的磁共振图像的像素值通过梯度编码和线圈灵敏度分布联系到子采样的磁共振信号的矩阵,这点都保持正确。 If included in the matrix is ​​positive definite, it may be safe to converge, the reconstructed pixel value linked to the matrix of the magnetic resonance image a magnetic resonance signal by the sub-sampling and encoding gradient coil sensitivity distribution, which maintain the correct point. CG算法在理论上在至多N2次迭代之后产生N2×N2系统的精确解。 CG algorithm produces exact solutions N2 × N2 system after N2 iterations up theoretically. 对于在128的范围内的N,虽然,它实际并不执行整个程序直到在数学上实现了严格的收敛。 For N in the range of 128, although it does not actually perform the entire procedure until mathematically rigorous achieve convergence. 然而,在实际中,在经过相对较少的次数的迭代之后,已经可以获得产生较好的诊断质量的重建的磁共振图像的近似。 However, in practice, after a relatively small number of iterations after the produce has been possible to obtain an approximate reconstruction of the magnetic resonance image of better diagnostic quality. 每个CG迭代步骤是包括将待求逆的矩阵乘以一残余矢量和几个不复杂的进一步的计算。 Each iteration step comprises a CG to be multiplied by the inverse matrix of a residual vector and a few uncomplicated further calculations. 因此,迭代速度关键取决于如何能够快速地执行矩阵矢量乘法。 Therefore, the speed of iteration depends crucially on how to quickly perform matrix-vector multiplication. 实现给定精度所需的迭代次数与所谓的待求逆的矩阵的状态和开始矢量的适应性相关。 Matrix achieve a state of a given number of iterations required to be so-called precision Inverse start vector and adaptive correlation. 由于根据本发明的方法的矩阵求逆的维数和大小,迭代求逆算法比例如直接求逆算法更快。 Because the inverse matrix of the method according to the present invention the size and dimension, the proportion Iterative inversion algorithm such as direct inversion algorithm faster. 例如通过Jacobi程序、Gauss-Seidel程序或共轭梯度(CG)法可以得到特别有利的结果。 For example, by a program Jacobi, Gauss-Seidel procedure, or the conjugate gradient (CG) method can be particularly advantageous results.

本发明还涉及适合于实施根据本发明的磁共振成像方法的磁共振成像系统。 The present invention further relates to a magnetic resonance imaging system the magnetic resonance imaging method of the present invention are suitable for implementation. 在独立权利要求8中限定了根据本发明的磁共振成像系统。 In a magnetic resonance imaging system 8 defines the invention according to the independent claims.

根据本发明的磁共振成像系统包括带有(微)处理器的计算机的控制单元,由此控制时间梯度场和RF激励。 The magnetic resonance imaging system of the present invention includes a computer with a (micro) processor control means, thereby controlling the time of the gradient field and RF excitation. 优选地是通过适当编程的计算机或(微)处理器或专用处理器实施根据本发明的磁共振成像系统的功能,这种计算机或(微)处理器或专用处理器带有专门设计用于执行根据本发明的一种或多种磁共振成像方法的集成电子或光电子电路。 Preferably by a suitably programmed computer or (micro) processor or a special purpose processor functional magnetic resonance imaging system according to an embodiment of the present invention, such a computer or (micro) processor or a special purpose processor designed to perform with integrated electronic or optoelectronic circuits according to one or more magnetic resonance imaging method according to the present invention.

本发明还涉及一种带有执行磁共振成像方法的指令的计算机程序。 The present invention further relates to a computer program of instructions for execution with the magnetic resonance imaging method. 本发明的进一步目的是提供一种计算机程序,由此能够实施根据本发明的一种或多种磁共振成像方法。 A further object of the present invention is to provide a computer program, thereby enabling the present invention to implement a magnetic resonance imaging method according to one or more. 在独立权利要求9中限定根据本发明的计算机程序。 9 is defined in the computer program of the present invention according to the independent claims. 当将根据本发明的计算机程序加载到磁共振成像系统的计算机中时,该磁共振成像系统执行根据本发明的一种或多种磁共振成像方法。 When loaded onto a computer a magnetic resonance imaging system, a computer program according to the present invention, the magnetic resonance imaging system to perform one or more magnetic resonance imaging method according to the invention. 因此,在根据本发明的计算机程序的指令的基础上,可以实现产生根据本发明的磁共振图像的技术效果。 Thus, on the basis of instructions of the computer program according to the present invention can be implemented on a magnetic resonance image produced according to the technical effects of the present invention. 例如,根据本发明的磁共振成像系统是一种其计算机装载有根据本发明的计算机程序的磁共振成像系统。 For example, magnetic resonance imaging system of the present invention is a computer which is loaded with a magnetic resonance imaging system according to the present invention is a computer program. 这种计算机程序可以存储在载体例如CD-ROM中。 Such a computer program may be stored in a carrier such as the CD-ROM. 然后从该载体中读取计算机程序(例如通过CD-ROM播放器)来将计算机程序加载到计算机中并将它存储在磁共振成像系统的计算机的存储器中。 The computer then reads the program from the carrier (e.g., a CD-ROM player) to be loaded into the computer program and stores it in the memory of the computer of the magnetic resonance imaging system of the computer. 然而,应该注意的是,还可以根据网络例如环球网将根据本发明的计算机程序加载到磁共振成像系统的计算机的存储器中。 However, it should be noted that, for example, the World Wide Web may also be loaded computer program according to the invention the memory of a computer a magnetic resonance imaging system according to the network.

参考下文以及附图所描述的实施例,通过非限制性的实例清楚地阐述本发明的这些和其它的方面。 Below with reference to the embodiments described and in the drawings, by way of non-limiting examples of the present invention clearly set forth these and other aspects.

附图概述该附图图解性地示出了在其中使用本发明的磁共振成像系统。 Brief Description of the drawings diagrammatically illustrates a magnetic resonance imaging system in which the present invention is used.

iii.附图描述该附图图解性示出了在其中使用本发明的磁共振成像系统。 III. Brief description of the drawings diagrammatically illustrates a magnetic resonance imaging system in which the present invention is used. 该磁共振成像系统包括一组主线圈10,由此产生了稳定的、均匀的磁场。 The magnetic resonance imaging system includes a set of main coils 10, thereby producing a stable, uniform magnetic field. 例如这样构造主线圈:它们围成了隧道状的检查空间。 Thus, for example, the main winding configuration: they enclose a tunnel-shaped examination space became. 要检查的患者滑进这个隧道状的检查空间中。 To check the patient slid into the tunnel-shaped examination space. 该磁共振成像系统还包括多个梯度线圈11,12,由此产生呈现空间变化的磁场尤其是在单独的方向上呈临时梯度形式的磁场,以叠加在均匀的磁场上。 The magnetic resonance imaging system further comprises a plurality of gradient coils 11, 12, thereby generating a spatially varying magnetic field exhibits particular in the form of a temporary form of a gradient magnetic field in a single direction, superimposed on the uniform magnetic field. 梯度线圈11,12连接到可控制的电源单元21。 Gradient coils 11, 12 may be connected to the power control unit 21. 通过电源单元21施加电流对梯度线圈11,12进行激励。 Applying a current to the gradient coils 11, 12 is excited by the power supply unit 21. 通过控制电源单元来控制梯度的强度、方向和持续时间。 To control the intensity, direction and duration of the gradient by controlling the power supply unit. 该磁共振成像系统还包括分别用于产生RF激励脉冲和拾取磁共振信号的发射和接收线圈13,16。 The magnetic resonance imaging system for generating further includes transmitting and receiving coils 13,16 RF excitation pulse and picking up the magnetic resonance signals. 发射线圈13优选构造为体线圈13,由此能够包围着要检查的目标(的一部分)。 Transmit coil 13 is preferably configured as a body coil 13, thereby surrounding the object to be examined (part). 通常这样在磁共振成像系统中设置体线圈:当他或她安置在磁共振成像系统中时体线圈13能够包围住要检查的患者30。 Typically such body coil arranged in the magnetic resonance imaging system: when he or she is placed in the magnetic resonance imaging system body coil 13 can surround the patient 30 to be examined live. 体线圈13用作发射RF激励脉冲和RF再聚焦脉冲的发射天线。 Body coil 13 acts as transmitting the RF excitation pulses and RF refocusing pulses transmit antenna. 优选地是,体线圈13包含所发射的RF脉冲(RFS)的在空间上的均匀强度分布。 Preferably, the uniform intensity RF pulses (RFS) comprising a body coil 13 is transmitted on the spatial distribution. 可以使用相同的线圈或天线可替换地作为发射线圈和接收线圈。 You may use the same coil or antenna may alternatively be used as transmit and receive coils. 此外,发射和接收线圈通常的形状为线圈,但是其它的其中发射和接收线圈用作电磁信号的发射和接收天线的几何形状也是可行的,发射和接收线圈13连接到电子发射和接收电路15上。 Furthermore, transmission and receiving coil is usually shaped as a coil, but other geometries where the transmission and receiving coil is used as an electromagnetic signal transmitting and receiving antenna are possible, transmitting and receiving coil 13 is connected to an electronic transmission and receiving circuit 15 .

应该注意的是,另外,使用单独的接收线圈16也是可能的。 It should be noted that additional, separate receiving coils 16 are also possible. 例如,使用表面线圈16作为接收线圈。 For example, a surface coil 16 as a receive coil. 这种表面线圈在相对较小的空间中具有高的灵敏度。 Such surface coils have a high sensitivity in a relatively small space. 发射线圈比如表面线圈连接到解调器24,通过解调器24对所接收的磁共振信号(MS)进行解调。 Transmitting coils such as surface coils are connected to a demodulator 24, demodulated by the magnetic resonance signals (MS) demodulator 24 the received. 将经解调的磁共振信号(DMS)施加到重建单元中。 The reconstruction unit is applied to the demodulated magnetic resonance signals (DMS). 接收线圈连接到前置放大器23。 Receiving coil 23 is connected to a preamplifier. 前置放大器23放大通过接收线圈16所接收的RF共振信号(MS),并将经放大的共振信号使用到解调器24中。 Preamplifier 23 amplifies the RF resonance signal (MS) received by the receiver coil 16, and to a demodulator 24 using the amplified resonance signal. 解调器24对经放大的共振信号进行解调。 The amplified demodulator 24 demodulates the resonance signals. 经解调的共振信号包含有涉及在对象的要成像的部位中的局部自旋密度的实际信息。 The demodulated resonance signal contains the actual information concerning the local spin portion of the object to be imaged in density. 此外,发射和接收电路15连接到调制器22。 Furthermore, transmission and receiving circuit 15 is connected to a modulator 22. 调制器22和发射和接收电路15启动发射线圈13以发射RF激励和再聚焦脉冲。 22 and transmission and receiving circuit 15 to start the modulator transmission coil 13 to transmit the RF excitation and refocusing pulses. 重建单元从所解调的磁共振信号(DMS)中得出一个或多个图像信号,该图像信号表示要检查的对象的成像部位的图像信息。 Reconstruction unit derived from one or more image signals magnetic resonance signals (DMS) demodulated, the image signal representing the image information of the imaging portion of the object to be examined. 在实际中优选地是将重建单元25构造为数字图像处理单元25,对这种数字图像处理单元25进行编程以从经解调的磁共振信号中得出表示对象的要成像部位的图像信息的图像信号。 The reconstruction unit 25 is configured as a digital image processing unit 25, such digital image processing unit 25 is preferably programmed in practice to derive from the demodulated magnetic resonance signals via said image information of an object to be imaged site of The image signal. 将在重建单元的输出中的信号施加到监测器26上,以便监测器显示磁共振图像。 The signal at the output of the reconstruction unit is applied to the monitor 26, so that the monitor displays a magnetic resonance image. 可替换的是,磁共振信号还可以表示三维密度分布。 Alternatively, the magnetic resonance signals may also represent the three-dimensional density distribution. 可以以多种方式将这种三维密度分布显示在监测器26上,例如显示使用者要选择的投影或立体图像对。 It can be a variety of ways such three-dimensional density profile displayed on a monitor 26, such as a display or a user to select the projected stereoscopic image pair. 还可替换的是,在等待进一步处理的同时还可以将来自重建单元25的信号存储在缓冲单元27中。 Alternatively also while awaiting further processing may also be a signal from the reconstruction unit 25 is stored in the buffer unit 27.

根据本发明的磁共振成像系统还具有包括(微)处理器的例如以计算机的形式的控制单元20。 The magnetic resonance imaging system of the invention further comprises having a (micro) processor, for example in the form of a computer control unit 20. 控制单元20控制RF激励的执行和临时梯度场的应用。 The control unit 20 controls the application of the temporary gradient fields and perform RF excitation. 为此,例如将根据本发明的计算机程序加载到控制单元20和重建单元25中。 For this purpose, for example, loaded into the control unit 20 and the reconstruction unit 25. The computer program of the invention.

从公知为SENSE方法的磁共振成像方法中可以得知,在所测量的磁共振信号(m)和亮度或对比值(I)之间存在如下的关系:I=(EHΨ-1E)-1EHΨ-1m (1) SENSE magnetic resonance imaging method is a method that can be known from, (m) and brightness or there is a relationship between the ratio of (I) to the magnetic resonance signals measured: I = (EHΨ-1E) -1EHΨ- 1m (1)

其中编码矩阵与根据磁共振信号的波矢量在k-空间中的空间编码以及根据灵敏度分布(sγ)(rp)的空间编码相关,这里下标γ表示相关的表面线圈,rp表示在要检查的对象中的相关的体积元素或体素的位置。 Wherein the encoding matrix in accordance with the wave vector of spatially encoding magnetic resonance signals in the k- space, and the sensitivity distribution (sγ) (rp) which encodes a space, where the subscripts γ indicates that the associated surface coil, to be checked represents the RP the position of the object associated with the volume elements or voxels. EH表示编码矩阵的复伴随矩阵。 EH represents the complex along with matrix-encoded matrix. 噪声相关矩阵表示为Ψ,它具有如下的矩阵元素:Ψγη=Στωγτστ2ωγη]]>这里στ表示在信号通道τ中的噪声标准偏差,ωγτ表示信号通道τ对在该信号通道γ中的噪声贡献的加权系数。 Noise correlation matrix expressed as Ψ, it has the following matrix elements: & Psi; & gamma; & eta; = & Sigma; & tau; & omega; & gamma; & tau; & sigma; & tau; 2 & omega; & gamma; & eta;]]> where στ represents the signal path noise standard deviation in τ, ωγτ signal path τ represents weighting coefficients noise contribution in the signal path of the γ.

编码矩阵E由此具有如下矩阵元素:Eγ,κ,ρ=sγ(rρ)eikκrρ---(2)]]>其中sγ(rp)表示在接收天线、特别是表面线圈γ的面积rp上的空间灵敏度分布。 Encoding matrix E thus has the following matrix elements: E & gamma;, & kappa;, & rho; = s & gamma; (r & rho;) eik & kappa; r & rho; --- (2)]]> where sγ (rp) indicates the receiving antenna, in particular space on the surface area of ​​the coil γ rp sensitivity distribution. 根据本发明,用块对角矩阵甚至用单位矩阵可对噪声相关矩阵Ψ进行充分地近似,尤其是在表面线圈电感去耦时更是这样。 According to the present invention, even with block diagonal matrix with a matrix of the noise correlation matrix Ψ can be approximated sufficiently, especially when the surface coil inductance decoupling even more so. 然后将有效编码减少为: It is then reduced to efficient encoding: 在更巧妙的方法中,在下面的机构不变时假设在不同的线圈之间的噪声相关随着时间恒定。 In a more subtle approach, assuming the noise in the correlation between different coils of the following mechanism during the same time with constant. 然后通过稀疏矩阵即带有简单结构的块对角矩阵描述接收器噪声:Ψ~(γ,κ),(γ′,κ′)=Ψγ,γ′δκ,κ′.]]>时间无关的矩阵Ψ可通过对在没有MR信号时所进行的基准噪声采样的统计分析实验地确定。 Then sparse matrix i.e. with block simple structure diagonal matrix described receiver noise: & Psi; ~ (& gamma;, kappa &;), (& gamma; & prime;, & kappa; & prime;) = & Psi; gamma &;, & gamma; & prime ; & delta; & kappa;, & kappa; & prime;.]]> matrix Ψ is independent of time can be determined by reference to the statistical noise in the absence of sampling MR signals analysis performed experimentally. 用ηγ表示第-通道的噪声输出,则Ψ的项由下式给出:Ψγ,γ′=ηγηγ′*‾,]]> With ηγ represents - noise output channels, then the Ψ term is given by: & Psi; gamma &;, & gamma; & prime; = & eta; & gamma; & eta; & gamma; & prime; * & OverBar;,]]>

这里上划线表示时间平均。 Here the dashed line represents a time average. 在本方法中,充分考虑了同时采集的磁共振信号的噪声相关性。 In the present method, fully considered noise magnetic resonance signals acquired simultaneously correlation.

使用这种简化的噪声统计法,通过简单的技巧就可以消除噪声方差矩阵。 Using this simplified noise statistics, through simple techniques can eliminate the noise covariance matrix. 基本思想的通过原始通道的线性组合产生一组实际的接收器通道,以使实际的通道具有单位噪声水平并没有相互的噪声相关性。 The basic idea of ​​generating a set of actual receiver channel by linearly combining the original channels, so that the actual channel unit having no mutual noise level and noise correlation. 为此通过由Cholesky分解获得的矩阵L的逆矩阵得出合适的加权系数:Ψ=LLH由此通过下式,具有去相关单元噪声的实际采样数据可从原始采样中获得:mγ,κdecorr=Σγ′(L-1)γ,γ′mγ′,κ.]]>与实际通道联系的净线圈灵敏度通过下式给出:sγdecorr(r)=Σγ′(L-1)γ,γ′sγ′(r),]]>(E^HE^)ρ,ρ′=Σγs^γ*(rρ)s^γ(rρ′)(∫e-ik(rρ-rρ′)(Σκδ(kκ-k))dk)]]>得到经修改的编码矩阵E(γ,κ),ρdecorr=eikκrρsγdecorr(rρ).]]>利用以这种方式修改的采样值和灵敏度,可以像处理一个物理通道一样处理新近组合的通道。 For this purpose draw the proper weighting coefficients matrix L inverse matrix of the Cholesky decomposition obtained: Ψ = LLH thereby by the following formula, having a de-correlation unit noise actual sampling data can be obtained from the original sampling: m & gamma;, & kappa; decorr = & Sigma; & gamma; & prime; (L-1) & gamma;, & gamma; & prime; m & gamma; & prime;, & kappa;]]> net coil sensitivity associated with the physical channel is given by:. s & gamma; decorr (r ) = & Sigma; & gamma; & prime; (L-1) & gamma;, & gamma; & prime; s & gamma; & prime; (r),]]> (E ^ HE ^) & rho;, & rho; & prime; = & Sigma; & gamma; s ^ & gamma; * (r & rho;) s ^ & gamma; (r & rho; & prime;) (& Integral; e-ik (r & rho; -r & rho; & prime;) (& Sigma; & kappa; & delta; (k & kappa; -k)) dk)] ]> to give the modified encoding matrix E (& gamma;, kappa &;), & rho; decorr = eik & kappa; r & rho; s & gamma; decorr (r & rho;).]]> sampling value, and sensitivity modified in this manner, as processing a physical channel processing channel as the newly combined. 实际通道的噪声方差矩阵是等于恒等的,因此当重新表述等式[6]以从经修改的数据中进行图像重建时可省去它。 Noise covariance matrix is ​​equal to the actual identity of the channel, so when re-expressed in Equation [6] In the time for image reconstruction from the modified data it may be omitted. 应该注意的是,通过变换到实际的通道,等式[6]的解并不改变(见附录B)。 It should be noted, by transforming the actual channel, Equation [6] the solution does not change (see Appendix B). 具体地说,保留了SNR的最佳化。 Specifically, retaining the best of the SNR.

在一方面,进行去相关,而在另一方面,忽略噪声相关,这两种选择到导致了相同的简化公式。 In one aspect, the de-correlation, on the other hand, ignoring the noise correlation, both selected to lead to the same simplified formula. 去掉用于去相关的上标,仍然将近似的编码矩阵表示为在两种情况(比较上文的公式(3))中它都读取的E: Superscript removed for decorrelation, the approximated still encoding matrix E is expressed in both cases (compare the above equation (3)) in which it is read:

现在由基准E表示近似的编码矩阵。 Now represents the approximate encoding matrix from the reference E. 已经发现,通过迭代求逆能够快速地数值地解决这种矩阵求逆问题。 It has been found to solve this problem by iterative matrix inversion inverse fast numerically. 数据m是磁共振信号的信号值(幅值和相位)。 M is a value of the data signal (magnitude and phase) magnetic resonance signals. 在(3)中的码包括反向傅立叶变换,因此 Code (3) comprises inverse Fourier transform, so 其中Ω是剩余码的一般表示,以区别于反向傅立叶变换。 Wherein Ω is a residue code represented in general, to distinguish inverse Fourier transform. 这可更精确地写为矢量和矩阵元素:(E^y)(γ,κ)=∫e-ikκr(Σρyρs^γ(rρ)δ(rρ-r)dr)]]>(E^Hm)ρ=Σγs^γ*(rρ)(∫e-iknrρ(Σκm(γ,κ)δ(kκ-k))dk)]]>以及为快速地执行反向傅立叶变换,在k-空间中在规则的正方形网格上对所测量的数据进行所谓的“网格化”变换:m=Gm,这里G例如是高斯卷积核:m~κ=ΣG(κ-κ′)m(κ′)---(5)]]>因此: This can be more accurately written as vector and matrix elements: (E ^ y) (& gamma;, kappa &;) = & Integral; e-ik & kappa; r (& Sigma; & rho; y & rho; s ^ & gamma; (r & rho;) & delta; ( r & rho; -r) dr)]]> (E ^ Hm) & rho; = & Sigma; & gamma; s ^ & gamma; * (r & rho;) (& Integral; e-iknr & rho; (& Sigma; & kappa; m (& gamma;, & kappa; ) & delta; (k & kappa; -k)) dk)]]> and to perform inverse fast Fourier transform on the measured data on a regular square grid in the k- space, the so-called "grid" transformation: m = Gm, where G, for example, a Gaussian convolution kernel: m ~ & kappa; = & Sigma; G (& kappa; - & kappa; & prime;) m (& kappa; prime &;) --- (5)]]> therefore: 其中通过公知的快速傅立叶变换(FFT)算法可以快速地执行反向傅立叶变换。 Wherein (FFT) algorithm may perform inverse fast Fourier transform by well-known fast Fourier transform. 使用Kaiser-Bessel窗和两倍(two-fold)过采样利用网格化预备的FFT有效地计算在这些表达式中的积分。 Using the Kaiser-Bessel window and double (two-fold) oversampling effectively integral calculation using these expressions meshing prepared FFT. 估算这些等式的每个等式的计算成本仅为N2logN的数量级,而常规的矩阵矢量乘法为N4的数量级。 Calculating the estimated cost of each of these equations equation only N2logN of magnitude, while the conventional matrix-vector multiplication of the order of N4. 存储在公式[5]中的函数f要求大约N2的存储器尺寸而不是直接存储 Stored function f formula [5] in the memory size required is approximately N2 instead stored directly 所需的N4。 Required N4. 对于 for 的重复计算,有利的是将网格化的方法分为两种方式:一种是首先计算并存储积分并执行普通的矩阵矢量乘法,一行一行地创建 Repeating the calculation, it is advantageous to gridding method is divided into two ways: one is to first calculate and store and perform common integrated matrix-vector multiplication, row by row to create 项而不存储它们。 Entries without storing them. 这个程序的优点在于它与通常比其它的方法收敛得更快的Gauss-Seidel方法兼容。 The advantage of this procedure is that it is compatible with other methods generally converge faster than the Gauss-Seidel method. 在另一方面,一个矩阵矢量乘法的复杂度仍然基本保持在N4。 In another aspect, a matrix-vector multiplication complexity still remained at N4.

另一种是通过两个连续的网格化和FFT步骤来执行 Another is performed by two consecutive steps and FFT grid 的计算。 Calculations. 这种方法的优点在于矩阵矢量乘法的成本仅为N2logN的数量级,并且该程序容易在并行处理硬件上执行。 The advantage of this method is that the matrix-vector multiplication magnitude N2logN costs only, and the program is easy to implement on a parallel processing hardware. 此外,通过迭代求逆从在码Ω中的剩余码中重建磁共振图像。 In addition, resonance image is reconstructed from the remaining code in the code Ω iterative inversion. 一般地说,这种迭代求逆可写为:I(i+1)=I(i)+αΔ(m(i),m(i-1)),这里信号数据m(i)是在剩余码Ω的基础上从所重建的图像数据I(i)中计算的。 In general, such an iterative inversion can be written as: I (i + 1) = I (i) + αΔ (m (i), m (i-1)), where the data signal m (i) is the remaining Ω on the basis of codes calculated from the reconstructed image data I (i) in. 每次在不同的函数Δ的基础上形成图像数据的新的估计I(i+1),这种新的估计每次更接近地适合通过磁共振信号所测量的信号数据。 The new estimate I (i + 1) each forming the image data on the basis of the different functions Δ, this new estimate more closely fit each signal data measured by the magnetic resonance signals. 迭代以图像数据I(0)估计和所测量的磁共振信号m(0)开始。 Iteration the image data I (0) and the estimated resonance signal m (0) is measured begin.

Claims (10)

1.一种形成磁共振图像的磁共振成像方法,其中借助接收天线通过多个信号通道采集磁共振信号,该单独的接收天线都具有各自的灵敏度分布,以及用噪声相关矩阵表示在单独的信号通道之间的噪声相关,其中利用子采样采集磁共振信号,在规则的采样网格上从所采集的磁共振信号中再采样出规则再采样的磁共振信号,以块对角矩阵或带对角矩阵对噪声相关矩阵进行近似,位于所近似的噪声相关矩阵的主对角线周围的预定带之外的矩阵元素的值为零,以及在灵敏度分布和近似噪声相关矩阵的基础上根据已经从所采集的磁共振信号中进行了采样的规则再采样的磁共振信号重建磁共振图像。 A magnetic resonance imaging method for forming a magnetic resonance image, acquired through the receiving antenna by means of which a plurality of signal channels of magnetic resonance signals, the single receive antenna having respective sensitivity profile, and a separate signal indicative of the noise correlation matrix a noise correlation between the channels, wherein the magnetic resonance signals acquired using the sub-sampling, the sampling in a regular grid resampling the sampled magnetic resonance signals from the rule and then the acquired magnetic resonance signals in a block diagonal matrix of the tape or diagonal matrix of the noise correlation matrix is ​​approximated value other than the predetermined matrix elements located with the main diagonal of the noise correlation matrix is ​​approximated around zero, and on the basis of the approximate sensitivity distribution and the noise correlation matrix in accordance with the already It was acquired magnetic resonance signals in a regularly sampled magnetic resonance signals resampled resonance image is reconstructed.
2.权利要求1所述的磁共振成像方法,其中近似的噪声相关矩阵是对角矩阵。 Magnetic resonance imaging method according to claim 1, wherein the approximate noise correlation matrix is ​​a diagonal matrix.
3.权利要求2所述的磁共振成像方法,其中,近似的噪声相关矩阵是单位矩阵。 Magnetic resonance imaging method according to claim 2, wherein the approximation of the noise correlation matrix is ​​an identity matrix.
4.权利要求1所述的磁共振成像方法,其中根据来自单独的信号通道的规则再采样的磁共振信号重建相应的接收线圈图像,以及磁共振图像是从接收线圈图像和灵敏度分布中得出的。 Magnetic resonance imaging method according to claim 1, the respective magnetic resonance signals wherein the image receiving coil according to the rules from the separate signal channel reconstruction resampling, and a magnetic resonance image is derived from the receiver coil images and the sensitivity distribution of.
5.权利要求1所述的磁共振成像方法,其中单独的接收天线的灵敏度分布基本彼此去耦。 Magnetic resonance imaging method according to claim 1, wherein the separate receive antenna sensitivity distribution substantially decoupled from one another.
6.权利要求1-5任一项所述的磁共振成像方法,其中磁共振图像是根据规则再采样的磁共振信号、通过迭代求逆算法进行重建的。 Magnetic resonance imaging method according to any of claim 1-5, wherein the magnetic resonance image a magnetic resonance signal is resampled according to the rules, inversion reconstruction algorithm iterations.
7.权利要求6所述的磁共振成像方法,其中磁共振图像是根据接收线圈图像、通过迭代求逆算法进行重建的。 Magnetic resonance imaging method according to claim 6, wherein a magnetic resonance image based on the image receiving coil, by an iterative inversion algorithm for reconstruction.
8.权利要求1-5任一项所述的磁共振成像方法,其中磁共振信号是在通过k-空间的轨迹的基础上进行采集的,该轨迹对应于在k-空间中的采样点的规则网格之外的所采集的磁共振信号的采样。 Magnetic resonance imaging method according to any of claim 1-5, wherein the magnetic resonance signal is acquired by the trajectory in k- space based on the trajectory corresponding to the sample points of the k- space magnetic resonance signals acquired outside of the regular grid.
9.权利要求8所述的磁共振成像方法,其中穿过k-空间的轨迹包括基本螺旋状的部分。 9. A magnetic resonance imaging method according to claim 8, wherein the through k- space trajectory comprises a substantially helical section.
10.一种磁共振系统,用于形成磁共振图像,该系统被设置成:通过接收天线并经过多个信号通道采集磁共振信号,该单独的接收天线都具有各自的灵敏度分布,以及用噪声相关矩阵表示在单独的信号通道之间的噪声相关,其中利用子采样采集磁共振信号,在规则的采样网格上从所采集的磁共振信号中再采样出规则再采样的磁共振信号,以块对角矩阵或带对角矩阵对噪声相关矩阵进行近似,位于所近似的噪声相关矩阵的主对角线周围的预定带之外的矩阵元素的值为零,以及在灵敏度分布和近似噪声相关矩阵的基础上根据已经从所采集的磁共振信号中进行了采样的规则再采样的磁共振信号重建磁共振图像。 10. A magnetic resonance system for forming a magnetic resonance image, which system is arranged to: receive antennas via a plurality of signal channels and through the acquisition of magnetic resonance signals, the single receive antenna having respective sensitivity profile, and the noise denotes a noise correlation matrix between the individual signal channels associated, wherein the magnetic resonance signals acquired using the sub-sampling, the sampling in a regular grid resampling the sampled magnetic resonance signals from the rule again acquired magnetic resonance signals in order to or a block diagonal matrix with a diagonal matrix of the noise correlation matrix is ​​approximated value other than the predetermined matrix elements located in the main diagonal band noise correlation matrix is ​​approximated around zero, and the associated noise in the approximate sensitivity distribution and the rules on the basis of the matrix have been sampled magnetic resonance signals acquired from the sampled magnetic resonance signals and then reconstructed magnetic resonance image.
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